Field of the Invention
The present invention relates to a device for the preparation of hot beverages by extraction, in particular for preparing coffee, having a beverage powder processing and metering unit, a hot water heater with a metering pump, and expulsion means for removing the used beverage powder from an extraction cup. Devices of this type are known in many forms, particularly for commercial use, and have proven excellent. The same type of devices for domestic use, however, with the same kind of ease of use have been available on the market only within the last few years. The previously known so-called espresso machines required an extraordinary amount of maintenance, which is an extreme disadvantage particularly for a consumer appliance. To guarantee satisfactory operation, two conditions are absolutely necessary, first, as few moving parts as possible, and second, simple cleaning of those parts that tend to become dirty.
These considerations were already taken into account in a device for making espresso coffee in accordance with German Published, Unexamined Patent Application DE-A-2912841. In this device, an extraction cup is used that is mounted stationary in the machine, while the powdered beverage processing and metering unit and the water heater are pivoted above the permanently mounted extraction cup. The filter cake is expelled by way of the low filter, which is guided into the extraction cup and is movable by a tappet. The expulsion of the filter cake from the lower filter is done passively, by a scraper on the pivotable brewing chamber. Besides the large mass that must be moved, there are also two components, which are active components, that must be moved, the control and actuation of which must accordingly be done at different positions. This kind of design is extremely complex and likely to need repairs.
By comparison, the device defining this generic type, in accordance with European Patent Application EP-A0,184,561, is considerably simpler in design and consequently less vulnerable to malfunction. In this device, the beverage powder processing and metering unit is permanently disposed in a housing, and the hot water heater and a metering pump are permanently mounted at different locations in the housing. The extraction cup moves only in a horizontal plane back and forth between the two units and to a third position, where expulsion means for removing the used beverage powder from the extraction cup are present. Although this device has already been considerably simplified over the previous one, nevertheless a large number of moving elements are still needed. The extraction cup must be pushed away from the powdered beverage processing and metering unit to the brewing station, and then moved by translation onward to the station in which the filter cake can be expelled by expulsion means, which additionally requires that the extraction cup be rotated; then, it must be rotated back again and moved back from the expulsion station to the metering unit. Other moving devices are needed for the upward and downward motion of the upper filter, which is conveyed into the extraction cup. A movable filter cake expeller is also needed. This latter provision can be achieved by a simple, passively actuated lever. However, removal of the extraction cup from the device to enable it to be cleaned is not readily possible. The complex guidance of the extraction cup does not allow simple removal thereof.
The device of European Patent Application EP-A-0,154,206 acknowledges that such devices require intensive maintenance. Correspondingly, it is proposed here that at least virtually all the parts of the device that are exposed to action by powdered beverage be combined into a structural unit that is detachably inserted into the housing of the device. Although this removable structural unit makes maintenance easier, it is still not suitable for the housewife performing the intermittently necessary cleaning of the filters. The parts combined into a structural unit must thus be replaced as a unit and sent to the factory for overhaul and cleaning. In this last version, the extraction cup is embodied by a piston/cylinder unit, which is movable up and down in its entirety, and is also pivotable.